The invention relates to a Jacquard machine, comprising on either side of the Jacquard machine at least two knife grids moving up and down in opposition.
The necessity to produce Jacquard machines operating at higher speeds at lower prices and, at the same time, sufficiently strong to be capable of forming the shed to suit the requirements in an accurate and reliable manner in order to realize a fabric of the quality desired, is putting an ever growing pressure on the construction of Jacquard machines. It is therefore important for the construction of Jacquard machines to make the knife drive, driving two sets of knives moving up and down in opposition, sufficiently rigid at a minimal cost. The two sets of knives moving up and down in opposition are taken up in a knife grid on either side of the Jacquard machine, such that both on the left and right side of the Jacquard machine (seen from the position of the weaver looking in the direction where the warp yarns are supplied) two knife grids are moving up and down in opposition.
In the cost price of a Jacquard machine, the costs for gearboxes to drive the motion of these knife grids as well as the components extending across the width of the Jacquard machine (from left to right) are of great consequence. Furthermore, the components, for instance, rocking levers, will not only become cheaper when it is possible to make them of more compact design, but the forces due to inertia will become less during their rocking motion, which is particularly favourable when realizing higher operational speeds with the Jacquard machine.
In EP 136 244 a solution is described where either side of the Jacquard machine is provided with a drive by means of an ordinary crank mechanism, each having a connecting rod driving two rocking levers, together driving the movable grids on one side of the Jacquard machine. The device is provided with a continuously rotating traversing shaft, linking up two ordinary crank mechanisms. The said rocking levers linked up are interconnected such that they are moving symmetrically and in opposition in order to minimize the forces on the straight guide way for realizing an almost vertical motion of the knife grids. This solution has the disadvantage that an expensive two-sided drive has to be provided. This disadvantage is still of more consequence in case the ordinary crank mechanism should be replaced by a gearbox with cams. Moreover the continuously rotating traversing shaft is situated below the knife grids, which is a disadvantage with respect to the accessibility of the Jacquard machine at the level of the selection system of the pulley system.
In EP 109 139 the problem of the accessibility is solved by installing the continuously rotating drive shaft, interlinking the two gearboxes, above the knife grids, crosswise in the centre of the Jacquard machine, each gearbox being provided with a set complementary cams, driving two cam followers situated diametrically opposed to each other. Each cam follower is linked up to or is part of a rocking lever, from which each of its extremities are linked with a different knife grid. Thus the accessibility of the selection systems and the pulley systems indeed having been improved, but two gearboxes are still required and the installation of the gearboxes, crosswise in the centre, will give cause to the need of big, expensive, heavy and heavily loaded rocking levers which extend along almost the total depth (crosswise distance) of the Jacquard machine. This will also strongly increase the inertia of the system.
In EP 754 791 a device is described with only one gearbox on one side, crosswise in the centre of the Jacquard machine, because of which a continuously rotating traversing shaft has become superfluous. The gearbox with its conjugated cams is driving two cam followers each of which is linked with a traversing rocking shaft, two levers being provided on each of the traversing rocking shafts, each of them driving one extremity of the knife grids on either side of the Jacquard machine. Moreover the two rocking shafts are of a coaxial design. This embodiment is offering a solution to limit the drives to only one gearbox, but it is still provided with two traversing rocking shafts, which in itself is already an expensive solution and which moreover, additionally is made still heavier because of the coaxial design of both shafts. Moreover, the levers, linked with these coaxial shafts are still extending almost along the total depth of the Jacquard machine, rendering the solution still more expensive and which has an increasing effect on the inertia.
In EP 1 475 465 a Jacquard machine is described, which on either side, is driven by an eccentric-connecting rod mechanism, the drive occurring crosswise in the centre of the Jacquard machine and both sides are linked by a continuously rotating shaft. Each eccentric-connecting rod mechanism is driving a traversing rocking shaft equipped with two rocking levers, one on either side of the Jacquard machine. The two rocking shafts are rocking in opposition and the rocking levers are extending almost along the entire depth of the Jacquard machine. With three traversing shafts, i.e. one continuously rotating shaft and 2 rocking shafts, this is not only an expensive solution, but also the accessibility is strongly restricted. Also the design of the large and heavy rocking levers still remains an expensive solution which has an inertia increasing effect.